nou lees dit eens , maar is al zo vaak besproken.
The nice thing about 745i tuning is that the user can select many different levels of performance. One does not have to spend a lot of money in order to get started with considerably higher power and torque levels.
The most economical and easiest way to get started is the
Motronic Chip Upgrade. In addition you only need a turbo pressure gauge and a simple valve to restrict air flow to the wastegate control hose (do not bleed the hose for higher boost!!!). More detailed information is in the Start-up Kit and Wastegate sections of these web-pages. This is a good way to start and to get the feeling of considerably higher power and torque. In this set up you should limit the boost to about 0.7-0.8 bar (300-330 hp/450-500 Nm). You can install the valve close to the Wastegate or into the cockpit (this is recommended as that same valve can then be used with the adjustable Wastegate, if you decide to upgrade). The max. full throttle boost in this set up is about 0.6-0.7 bar giving 0-100 km/h acceleration of approx. 6.3-6.5 s., which is already an exellent figure for any automatic sports car. More importantly, the middle range boost is about 0.7-0.9 bar giving tremendous acceleration in the 60-160 km/h speed range.
This modification to the 745 Motronic computer program allows unlimited increase in power and torque. The practical increase is dependent on several other setups in the car and engine. Typical increase is 100-150 hp together with some modification of wastegate or to wastegate's control system. Power levels of 350 - 500+ HP and torque over 640 Nm are possible.
There are many ways to increase boost. You can either have a fixed boost level or a adjustable boost control. One of the best boost control systems for 745's was the Tuoma Perfection adjustable wastegate, but that is not available at the moment and may not be manufactured at all anymore.
The standard 745i 3.4 L engine gives 252 HP at 0.3/0.5 bar boost. Engine cutoff is set to 0,7 bar, which many of the 745 owners have unfortunately experienced.
This modification to the computer program removes the cutoff limit and sets all necessary parameters for unlimited power. The program is dynamic, so performance is optimal at any and no boost conditions. Torque is increased also considerably.
As a rule of thumb this program increases power by approx. 50 HP for each 0.2 bar step:
0.7 bar = 300 HP, 0.9 bar = 350 HP, 1.1 bar = 400 HP, 1.3 bar = 450 HP, etc...
The standard 745 turbo is good at least upto 1.5 bar, but we have not calculated or tested it at higher boost levels.
zo 16 jun 2013, 19:17
